1. Field of the Invention
The present invention relates to a method of making an assembly. More particularly, the present invention is directed towards the method of making a threaded insert assembly wherein the insert's threads are captured and rotatably held after it is inserted, and further, where the insert cannot be removed by normal means after the capture.
2. Background of the Invention
There has been a long felt need, since the advent of multiple stamped assemblies which incorporate threaded inserts, to eliminate the need to attend to each threaded insert individually in order to insert and/or screw it into the stamping.
The present methods are characterized by being slow, costly, and are often labor intensive. For example at present, when screw-type wire fastener inserts are installed in electrical socket terminal strips which are stamped from sheet metal, either a self-threading type screw is used or most commonly the hole is tapped prior to screwing in a machine screw.
Terminal strips of the type described are usually stamped in complex strips having a plurality of repetitive configurations, each requiring one or more theaded inserts. Often each insert must be screwed to have its head within a specified distance from the strip to leave room for wire wrap as a convenience for the user. Finally, as an added convenience, or safety factor as the case may be, the tip of the insert is struck to deform the threads thereby providing a portion which resists accidental removal of the screw from the assembly.
It is quite apparent that either each fastener requires much manual attention during assembly or automation calls for relatively slow sequential installation or complicated and expensive machinery for simultaneous installation.
Another consideration in the aforedescribed stamped sheet metal assembly comes to point when the sheet metal is relatively thin. This consideration is retaining strength. Threads often strip when the fastener is put under load in use. This is often addressed by extruding the hole in which the fastener is installed, to form a circular flange, thereby increasing the thread holding area. The present invention operates to include this feature when advisable.